Sound insulation sheet member and sound insulation structure using same

ABSTRACT

An object of the present invention is to provide a structural body that has high vibration damping and high sound-insulating performance which exceeds mass law while being relatively light weight, that is highly flexible in design, excellent in versatility, and easy to manufacture so that productivity and economic efficiency can be improved. The object thereof is achieved with a sheet member of a sheet having a thickness of 1 mm or less and having rubber elasticity and a resonant portion, wherein the resonant portion is provided in contact with a surface of the sheet, the resonant portion including a base part and a weight part, and the weight part being supported by the base part and having a larger mass than the base part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of prior U.S. applicationSer. No. 17/490,070, filed Sep. 30, 2021, the disclosure of which isincorporated herein by reference in its entirety. U.S. application Ser.No. 17/490,070 is a continuation of U.S. application Ser. No.16/053,278, filed on Aug. 2, 2018, issued as U.S. Pat. No. 11,168,474,on Nov. 9, 2021, which is a continuation of International ApplicationNo. PCT/JP2017/003985, filed on Feb. 3, 2017, and designated the U.S.,and claims priority from Japanese Patent Application No. 2016-020049which was filed on Feb. 4, 2016, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a sound insulating sheet member and asound insulating structural body using the same.

BACKGROUND ART

Buildings such as apartments, office buildings, and hotels, requireinsulation from outdoor noise such as automobiles, trains, airplanes,ships, and the like and equipment noise and human voice that occur inthe buildings to keep quietness suitable for room use. Additionally, invehicles such as automobiles, trains, airplanes, and ships, it isnecessary to insulate wind noise and engine noise to reduce indoor noiseso that passengers are provided with a quiet and comfortable space. Tothis end, research and development have been made to explore means forblocking propagation of noise and vibration from outdoor to indoor orfrom outside to inside the vehicles, i.e., vibration damping and soundinsulating means. Recently, buildings have required light-weightvibration damping and sound insulating members due to high-rise buildingconstruction and the like, and vehicles also have required light-weightvibration damping and sound insulating members for improving energyefficiency. Furthermore, in order to improve design flexibility ofbuildings, vehicles, and equipment thereof, there has been a desire fora vibration damping and sound insulating member adaptable to intricateshapes.

In general, properties of a vibration damping and sound insulatingmaterial follow the so-called mass law. In other words, transmissionloss, which is an index of the amount of reduced noise, is determined bya logarithm of a product of the mass of the vibration damping and soundinsulating material multiplied by the frequency of an acoustic wave or asound wave. Accordingly, in order to increase reduction of a noisehaving a certain constant frequency, the mass of the vibration dampingand sound insulating material needs to be increased. However, increasingthe mass of the vibration damping and sound insulating material limitsthe amount of noise reduction due to restrictions to the masses ofbuildings, vehicles, and the like.

To solve the problem of increase in the mass of a vibration damping andsound insulating member, improvement of member structure hasconventionally been made. Examples of known methods include combined useof a plurality of rigid flat plate materials, such as gypsum boards,concrete, steel plates, glass plates, or resin plates and use of ahollow double-wall structure or a hollow triple-wall structure using agypsum board or the like.

And in recent years, in order to achieve such sound insulatingperformance that exceeds mass law, sound insulating plates made of aplate-type acoustic metamaterial have been proposed in which a highlyrigid flat plate material and resonators are used in combination.Specifically, there have been proposed sound insulating plates providedwith a plurality of independent stubby projections (resonators) made ofsilicone rubber and tungsten or a plurality of independent stubbyprojections (resonators) made of rubber on an aluminum substrate (seeNon-Patent Literature 1 and 2) and a sound insulating plate providedwith a plurality of independent stubby projections (resonators) made ofsilicone rubber or silicone rubber and a lead cap on an epoxy substrate((see Non-Patent Literature 3).

CITATION LIST Non-Patent Literature

-   Non-Patent Literature 1: M. B. Assouar, M. Senesi, M. Oudich, M.    Ruzzene and Z. Hou, Broadband plate-type acoustic metamaterial for    low-frequency sound attenuation, Applied Physics Letters, 2012,    volume 101, pp 173505.-   Non-Patent Literature 2: M. Oudich, B. Djafari-Rouhani, Y.    Pennec, M. B. Assouar, and B. Bonello, Negative effective mass    density of acoustic metamaterial plate decorated with low frequency    resonant pillars, Journal of Applied Physics, 2014, volume 116, pp    184504.-   Non-Patent Literature 3: M. Oudich, Y. Li, M. B. Assouar, and Z.    Hou, A sonic band gap based on the locally resonant phononic plates    with stubs, New Journal of Physics, 2010, volume 12, pp 083049.

SUMMARY OF INVENTION Technical Problem

Non-Patent Literature 1 to 3 have considered sound insulatingperformance in changing the material and size of the stubby projections(resonators). However, when improving sound insulating performance bymerely changing the material and size of the stubby projections(resonators), design flexibility has been limited.

In addition, the sound insulating plates disclosed in Non-PatentLiterature 1 to 3, which had the individual resonators arranged on thesubstrate by using an adhesive, were complicated in manufacturingprocess, and thus inferior in productivity and economic efficiency.Moreover, the sound insulating plates disclosed in Non-Patent Literature1 to 3 use the relatively rigid aluminum substrate or epoxy substrate,and thus cannot easily be deformed. Accordingly, for example, the soundinsulating plates cannot be arranged along a non-flat surface such as acurved surface.

As a solution to the problem, it is considerable that an aluminumsubstrate or epoxy substrate curvedly molded in advance is employed toprovide a plurality of resonators on the curved surfaces of thesubstrates. However, in this structure, the individual resonators needto be arranged on the curved surface, so that the manufacturing processbecomes more difficult, which further deteriorates productivity andeconomic efficiency. In addition, preparing every time a substratecorresponding to the curved shape of an arrangement place lacksversatility. Therefore, for enlargement of industrial applicability, asound insulating sheet member based on a new design concept has beendesired, particularly from the viewpoints of design flexibility,versatility, productivity, cost, and the like.

The present invention has been made in view of the above background art.It is an object of the present invention to provide a sound insulatingsheet member that has high sound-insulating performance which exceedsthe mass law while being relatively light weight, that is highlyflexible in design, excellent in versatility, and easy to manufacture sothat productivity and economic efficiency can be improved, and a soundinsulating structural body using the same.

It is to be noted that the present invention is not limited to theobject mentioned above, and another object of the invention can be toachieve functions and effects that are obtained from respectivearrangements illustrated in embodiments of the invention describedbelow, and that are not obtained by the conventional techniques.

Solution to Problem

The present inventors conducted intensive and extensive studies to solvethe above problems. As a result, the present inventors found out thatthe problems can be solved by employing a sheet member including a sheethaving rubber elasticity and a plurality of resonant portions providedon the sheet, and completed the present invention.

Specifically, the present invention provides the following variousspecific aspects:

[1] A sound insulating sheet member including at least a sheet havingrubber elasticity and a plurality of resonant portions, in which theresonant portions are provided in contact with a sheet surface of thesheet, each of the resonant portions including a base part and a weightpart, and the weight part being supported by the base part and having alarger mass than the base part.

[2] The sound insulating sheet member according to the [1], in which thesheet includes at least one selected from a group consisting ofthermosetting or photocurable elastomers and thermoplastic elastomers.

[3] The sound insulating sheet member according to the [1] or [2], inwhich the sheet has a Young's modulus of from 0.01 MPa to 100 MPa.

[4] The sound insulating sheet member according to any of the [1] to[3], in which the base part includes at least one selected from a groupconsisting of thermosetting or photocurable elastomers, thermoplasticelastomers, thermosetting or photocurable resins, and thermoplasticresins.

[5] The sound insulating sheet member according to any of the [1] to[4], in which the sheet and the resonant portions are an integrallymolded article, and both together include at least one selected from thegroup consisting of thermosetting or photocurable elastomers andthermoplastic elastomers.

[6] The sound insulating sheet member according to any of the [1] to[5], in which the weight part includes at least one selected from agroup consisting of metals, alloys, and inorganic glasses.

[7] The sound insulating sheet member according to any of the [1] to[6], in which at least a part of the weight part is embedded in the basepart.

[8] The sound insulating sheet member according to any of the [1] to[7], in which the weight part includes a protruding part provided towardthe base part.

[9] The sound insulating sheet member according to any of the [1] to[8], further including at least one or more rib-like projectingportions, in which the rib-like projecting portions are provided incontact with the sheet surface of the sheet, and have a height higherthan the resonant portions in a sheet normal direction.

[10] The sound insulating sheet member according to the [9], in whichthe rib-like projecting portions are provided so as to extend in a sheetlength direction of the sheet.

[11] The sound insulating sheet member according to the [9] or [10], inwhich a plurality of the rib-like projecting portions are spaced apartalong the sheet length direction of the sheet.

[12] The sound insulating sheet member according to any of the [9] to[11], in which the sheet, the resonant portions, and the rib-likeprojecting portions are an integrally molded article, and all togetherinclude at least one selected from the group consisting of thermosettingor photocurable elastomers and thermoplastic elastomers.

[13] A sound insulating structural body including at least the soundinsulating sheet member according to any of the [1] to and a supportbody, in which the support body is provided in contact with at least onesurface of the sheet of the sound insulating sheet member, and supportsthe sheet.

[14] The sound insulating structural body according to the [13], inwhich the support body has a Young's modulus of 1 GPa or more.

[15] A sound insulating structural body including the sound insulatingsheet member according to any of the [1] to and a flame retardant and/ornonflammable member.

[16] A sound insulating structural body that is a layered body includingthe sound insulating sheet member according to any of the [1] to [12].

[17] A method for manufacturing a sound insulating sheet member,including the following steps of:

-   -   (1) preparing a mold provided with a plurality of cavities and        arranging a weight in each of the plurality of cavities provided        in the mold;    -   (2) pouring a resin material and/or polymer material in the        cavities,    -   (3) curing the poured resin material and/or polymer material;        and    -   (4) releasing the resulting cured article from the mold.

[18] The method for manufacturing a sound insulating sheet memberaccording to the [17], in which bottoms of the cavities arehemispherical.

Advantageous Effects of Invention

The present invention can provide a sound insulating sheet member thathas high sound-insulating performance which exceeds mass low while beingrelatively light weight, that is highly flexible in design, excellent inversatility, and easy to manufacture so that productivity and economicefficiency can be improved, and a sound insulating structural body usingthe same.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view illustrating a sound insulatingsheet member and a sound insulating structural body according to a firstembodiment.

FIG. 2 is a cross-sectional view taken along arrows II-II of FIG. 1 .

FIG. 3 is a diagram illustrating an example of a step in manufacturingthe sound insulating sheet member.

FIG. 4 is a diagram illustrating an example of a step in manufacturingthe sound insulating sheet member.

FIG. 5 is a diagram illustrating an example of a step in manufacturingthe sound insulating sheet member.

FIG. 6 is a diagram illustrating an example of a step in manufacturingthe sound insulating sheet member.

FIG. 7 is a schematic perspective view illustrating a sound insulatingsheet member and a sound insulating structural body according to asecond embodiment.

FIG. 8 is a cross-sectional view taken along arrows VIII-VIII of FIG. 7.

FIG. 9 is a schematic perspective view illustrating a weight part of thesound insulating sheet member and the sound insulating structural bodyof the second embodiment.

FIG. 10 is a schematic perspective view illustrating a weight part as amodified example.

FIG. 11 is a schematic perspective view illustrating a weight part as amodified example.

FIG. 12 is a graph illustrating the sound insulating performance ofExample 1.

FIG. 13 is a graph illustrating the sound insulating performance ofComparative Example 1.

FIG. 14 is a graph illustrating the sound insulating performance ofComparative Example 2.

FIG. 15 is a graph illustrating the sound insulating performance ofComparative Example 3.

FIG. 16 is a graph illustrating the sound insulating performance ofComparative Example 4.

FIG. 17 is a graph illustrating the sound insulating performance ofComparative Example 5.

FIG. 18 is schematic structural view of unit cells used for estimationof acoustic band gap.

FIG. 19 is a schematic perspective view illustrating a sound insulatingsheet member and a sound insulating structural body according to a thirdembodiment.

FIG. 20 is a cross-sectional view taken along arrows XX-XX of FIG. 19 .

FIG. 21 is a diagram illustrating an example of the sound insulatingstructural body.

MODE FOR CARRYING OUT THE INVENTION

A sound insulating sheet member according to the present inventionincludes at least a sheet having rubber elasticity and a plurality ofresonant portions, in which the resonant portions are provided incontact with a sheet surface of the sheet, each of the resonant portionsincluding a base part and a weight part, and the weight part beingsupported by the base part and having a larger mass than the base part.

Hereinafter, each embodiment of the present invention will be describedwith reference to the drawings. It should be noted that each embodimentbelow is merely exemplary to illustrate the present invention, and thepresent invention is not limited to only the embodiments. In addition,hereinbelow, it should be noted that positional relationships such asvertical and lateral relationships are based on those illustrated in thedrawings unless otherwise specified. Additionally, dimensional scalesfor the drawings are not limited to those illustrated in the drawings.Note that, in the present specification, the representation of anumerical range of, for example, “from 1 to 100” encompasses both of thelower limit value “1” and the upper limit value “100”. This also appliesto representations of other numerical ranges.

First Embodiment

FIG. 1 and FIG. 2 are a schematic perspective view illustrating a soundinsulating sheet member 100 and a sound insulating structural body 200of the present embodiment and a cross-sectional view taken along arrowsII-II thereof. The sound insulating sheet member 100 includes a sheet 11having rubber elasticity, a plurality of resonant portions 21 providedin contact with a sheet surface 11 a of the sheet 11, and at least oneor more rib-like projecting portions 31 provided on the sheet surface 11a. The sound insulating sheet member 100 is supported by a support body51 provided on a sheet surface 11 b side of the sheet 11, whereby thesound insulating structural body 200 is formed.

In the sound insulating sheet member 100 and the sound insulatingstructural body 200, for example, when a sound wave is input from anoise source located on the support body 51 side, resonance of the sheet11 and/or the resonant portions 21 occurs. In this case, there can exista frequency region in which the direction of a force acting on thesupport body 51 is opposite to the direction of an accelerationoccurring at the sheet 11 and/or the resonant portions 21. Thus, apartor all of the vibration having a specific frequency is cancelled out,which creates a complete acoustic band gap where the vibration having aspecific frequency is almost completely gone. Due to this, the part orall of the vibration comes to rest in the vicinity of a resonancefrequency of the sheet 11 and/or the resonant portions 21, as a resultof which high sound-insulating performance that exceeds mass law can beobtained. A sound-insulating member using such as a principle is calledan acoustic metamaterial. Hereinafter, respective constituent elementsof the sound insulating sheet member 100 and the sound insulatingstructural body 200 of the present embodiment will be described indetail.

[Sheet]

The sheet 11 is a sheet having rubber elasticity. Although notparticularly limited, the sheet 11 may have rubber elasticity due tomolecular motion of a resin (an organic polymer) or the like. The sheet11 is capable of functioning as a vibrator (a resonator) that vibratesat a certain frequency when a sound wave is input from a noise source.

As a material forming the sheet 11, the sheet 11 preferably includes atleast one selected from a group consisting of thermosetting orphotocurable elastomers and thermoplastic elastomers. Thermosettingelastomers or thermoplastic elastomers are more preferably used, becauseirradiated light may hardly reach the center part as the thickness ofthe sheet 11 is larger.

Specific examples of the material include thermosetting elastomers,including vulcanized rubbers such as chemically cross-linked naturalrubber or synthetic rubber and thermosetting resin-based elastomers suchas urethane rubber, silicone rubber, fluorine rubber, and acrylicrubber; thermoplastic elastomers, including olefin-based thermoplasticelastomers, styrene-based thermoplastic elastomers, vinyl chloride-basedthermoplastic elastomers, urethane-based thermoplastic elastomers,ester-based thermoplastic elastomers, amide-based thermoplasticelastomers, silicone rubber-based thermoplastic elastomers, and acrylicthermoplastic elastomers; and photocurable elastomers, including acrylicphotocurable elastomers, silicone-based photocurable elastomers, andepoxy-based photocurable elastomers. More specifically, there may bementioned natural rubber, isoprene rubber, butadiene rubber,styrene-butadiene rubber, chloroprene rubber, nitrile rubber,polyisobutylene rubber, ethylene-propylene rubber, chlorosulfonatedpolyethylene rubber, acrylic rubber, fluorine rubber, epichlorohydrinrubber, polyester rubber, urethane rubber, silicone rubber, modifiedproducts thereof, and the like, although not particularly limitedthereto. These materials can be used singly or in combination of two ormore thereof. Among them, preferred are natural rubber, isoprene rubber,butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrilerubber, polyisobutylene rubber, ethylene-propylene rubber,chlorosulfonated polyethylene rubber, acrylic rubber, fluorine rubber,epichlorohydrin rubber, polyester rubber, urethane rubber, siliconerubber, and modified products thereof, and more preferred are siliconerubber, acrylic rubber, and modified products thereof from theviewpoints of excellent heat resistance, excellent cold resistance, andthe like.

The sheet 11 may include various kinds of additives, such as a flameretardant, an antioxidant, and a plasticizer, as long as it is a sheetexhibiting the so-called rubber elasticity. Flame retardants areadditives that are added to prevent flammable materials from easilyburning or igniting. Specific examples thereof include bromine compoundssuch as pentabromodiphenyl ether, octabromodiphenyl ether,decabromodiphenyl ether, tetrabromobisphenol A, hexabromo cyclododecane,and hexabromobenzene, phosphorus compounds such as triphenyl phosphate,chlorine compounds such as chlorinated paraffins, antimony compoundssuch as antimony trioxide, metal hydroxides such as aluminum hydroxide,nitrogen compounds such as melamine cyanurate, and boron compounds suchas sodium borate, although not particularly limited thereto.Additionally, antioxidants are additives that are added to preventoxidative degradation. Specific examples thereof include phenolicantioxidants, sulfur antioxidants, and phosphorus antioxidants, althoughnot particularly limited thereto. Furthermore, plasticizers areadditives that are added to improve flexibility and weather resistance.Specific examples thereof include phthalic acid ester, adipic acidester, trimellitic acid ester, polyester, phosphoric acid ester, citricacid ester, sebacic acid ester, azelaic acid ester, maleic acid ester,silicone oil, mineral oil, vegetable oil, and modified products thereof,although not particularly limited thereto. These can be used singly orin combination of two or more thereof.

In the present embodiment, the sheet 11 is formed into a square shape inplan view, but the shape thereof is not particularly limited thereto.Any plan view shape can be employed, such as any of polygonal shapesincluding triangular, oblong, rectangular, trapezoidal, rhombic,pentagonal, and hexagonal shapes, circular shapes, elliptical shapes,and irregular shapes that are not classified into these shapes. Notethat the sheet 11 may have a cutout portion, a punched-out hole, or thelike at anyplace as long as properties of the acoustic metamaterial arenot impaired, from the viewpoints of improvement of stretchability,weight reduction, and the like.

The thickness of the sheet 11 is not particularly limited. The thicknessof the sheet 11 also enables control of a frequency band where highsound-insulating performance is exhibited (an acoustic band gap widthand a frequency position). Thus, the thickness of the sheet 11 can beset as appropriate so that the acoustic band gap is coincident with adesired sound insulation frequency region. When the thickness of thesheet 11 is large, the acoustic band gap width is narrowed, and tends toshift to a low frequency side. Alternatively, when the sheet 11 has asmall thickness, the acoustic band gap width is widened, and tends toshift to a high frequency side. From the viewpoints of sound-insulatingperformance, mechanical strength, flexibility, handleability, and thelike, the thickness of the sheet 11 is preferably 50 μm or more, morepreferably 100 μm or more, and still more preferably 200 μm or more.Additionally, the thickness of the sheet 11 is preferably 10 mm or less,more preferably 1 mm or less, and still more preferably 500 μm or less.

Herein, from the viewpoints of sound-insulating performance, mechanicalstrength, flexibility, handleability, productivity, and the like, thesheet 11 has a Young's modulus of preferably 0.01 MPa or more, and morepreferably 0.1 MPa or more, and has a Young's modulus of preferably 100MPa or less, and more preferably of 10 MPa or less. As used herein, theterm Young's modulus in the present specification means a ratio of aforce (stress) acting on per unit cross-sectional area of a specimen anda deformation rate (strain) when an external force is applied in auniaxial direction, and means a value of a storage normal modulus at and10 Hz, measured by a forced oscillation non-resonance method in JIS K6394: 2007 “Rubber, vulcanized or thermoplastic—Determination of dynamicproperties—”.

Additionally, from the viewpoint of reduction of temperature dependenceof sound-insulating performance at low temperature, the sheet 11 has aglass transition temperature of preferably 0° C. or less. The lower theglass transition temperature of the sheet 11, the higher the coldresistance. Thus, the temperature dependence of Young's modulus in thevicinity of 0° C. becomes small, and sound-insulating performance tendsto hardly depend on environmental temperature. The glass transitiontemperature is more preferably −10° C. or less, still more preferably−20° C. or less, and particularly preferably −30° C. or less. Note that,in the present specification, the glass transition temperature of thesheet 11 means a peak temperature of a tangent of the loss angle indynamic viscoelasticity measurement at the frequency of 10 Hz describedabove, particularly, temperature dependence measurement.

[Resonant Portion]

The resonant portions 21 function as vibrators (resonators) that vibrateat a certain frequency when a sound wave is input from a noise source.The resonant portions 21 of the present embodiment each are formed by acomposite structural body including a base part 22 and a weight part 23that is supported by the base part 22 and that has a larger mass thanthe base part 22. Each of the resonant portions 21, which has such acomposite structural body, functions effectively as a resonator having aresonance frequency that is determined by the mass of the weight part 23working as a weight and the spring constant of the base part 22 workingas a spring.

The array of the resonant portions 21, the number thereof to bearranged, the size thereof, and the like can be determined asappropriate according to desired performance, and are not particularlylimited. The resonant portions 21 are provided in contact with at leastone sheet surface of the sheet. For example, in the present embodiment,the plurality of resonant portions 21 are arranged at an equal intervalin a matrix form, although the array of the resonant portions 21 is notparticularly limited thereto. For example, the plurality of the resonantportions 21 may be arranged in a staggered manner or at random. Thesound-insulating mechanism by the sheet does not use Bragg scattering,as in the so-called phononic crystals, and therefore the resonantportions 21 do not necessarily have to be arranged at a regular andperiodic interval.

In addition, the number of the resonant portions 21 to be arranged perunit area is not particularly limited as long as the resonant portions21 can be arranged so as to prevent mutual interference due to contacttherebetween or other reason. The maximum number of the resonantportions 21 per unit area varies depending on the shape and the like ofthe resonant portions 21. For example, when the resonant portions 21have a cylindrical shape whose height direction is disposed in parallelto a sheet normal direction and whose cylindrical cross-sectionaldiameter is 1 cm, 100 pieces or less per 10 cm 2 are preferable.Additionally, regarding the minimum number of the resonant portions 21per unit area, for example, when the resonant portions 21 have acylindrical shape whose height direction is disposed in parallel to thesheet normal direction and whose cross-sectional diameter is 1 cm, 2pieces or more per 10 cm 2 are preferable, 10 pieces or more per 10 cm 2are more preferable, and 50 pieces or more per 10 cm 2 are still morepreferable. By arranging such that the number of the resonant portions21 falls within the above preferable lower limit or more, highersound-insulating performance tends to be obtainable. In addition,arranging such that the number of the resonant portions 21 falls withinthe above preferable upper limit or less facilitates achievement ofweight reduction of the entire sheet.

A maximum height H1 of the resonant portions 21 in the normal directionof the sheet 11 can be set as appropriate according to desiredperformance, and is not particularly limited. From the viewpoints ofmolding easiness, productivity improvement, and the like, the maximumheight H1 is preferably from 50 μm to 100 mm, more preferably from 100μm to 50 mm, and still more preferably from 1 mm to 20 mm. Setting themaximum height H1 within the above preferable numerical rangefacilitates winding and stacking of the sheet 11 (i.e., the soundinsulating sheet member 100) provided with the resonant portions 21thereon, thereby enabling manufacturing and storage thereof in theso-called roll-to-roll manner, so that productivity and economicefficiency tend to be improved.

[Base Part]

In the present embodiment, a plurality of base parts 22 having asubstantially cylindrical outer shape are provided in contact with asheet surface 11 a of the sheet 11. Inside the base parts 22 areembedded each weight part 23 having a substantially cylindrical outershape. The outer shape of the base parts 22 is not particularly limited,and any shape can be employed, such as any of polygonal prism-likeshapes including a triangular prism-like shape, a rectangular prism-likeshape, a trapezoidal prism-like shape, a pentagonal prism-like shape,and a hexagonal prism-like shape, cylindrical shapes, ellipticcylindrical shapes, truncated pyramid shapes, truncated cone shapes,pyramid shapes, cone shapes, hollow tubular shapes, branched shapes, andirregular shapes that are not classified into these shapes. In addition,the base parts 22 can be formed into a columnar shape having across-sectional area and/or cross-sectional shape varying depending onthe height position of the base parts 22.

The material of the base parts 22 is not particularly limited as long asthe material satisfies the above-mentioned required characteristics.Examples of the material include polymer materials, in which there maybe mentioned at least one selected from a group consisting ofthermosetting or photocurable elastomers, thermoplastic elastomers,thermosetting or photocurable resins, and thermoplastic resins.

Examples of the thermosetting or photocurable elastomers andthermoplastic elastomers include those exemplified for the sheet.Examples of the thermosetting or photocurable resins include acrylicthermosetting resins, urethane-based thermosetting resins,silicone-based thermosetting resins, and epoxy-based thermosettingresins. Examples of the thermoplastic resins include polyolefin-basedthermoplastic resins, polyester-based thermoplastic resins, acrylicthermoplastic resins, urethane-based thermoplastic resins, andpolycarbonate-based thermoplastic resins.

Specific examples thereof include rubbers, including vulcanized rubberssuch as chemically cross-linked natural rubber or synthetic rubber,isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprenerubber, nitrile rubber, polyisobutylene rubber, ethylene propylenerubber, chlorosulfonated polyethylene rubber, acrylic rubber, fluorinerubber, epichlorohydrin rubber, polyester rubber, urethane rubber,silicone rubber, and modified products thereof; and polymers such aspolyacrylonitrile, polyvinyl chloride, polychlorotrifluoroethylene,polyethylene, polypropylene, polynorbornene, polyether ether ketone,polyphenylene sulfide, polyarylate, polycarbonate, polystyrene, epoxyresin, and oxazine resin, although not particularly limited thereto.These can be used singly or in combination of two or more thereof.Additionally, the base parts 22 may be composed of a porous bodyincluding pores (a gas such as air) in any of these polymer materials.Furthermore, the base parts 22 may include a liquid material such asmineral oil, vegetable oil, or silicone oil. Note that, when the baseparts 22 include a liquid material, the liquid material is desirablysealed in a polymer material from the viewpoint of prevention of outwardleakage of the liquid material.

Among these, the material of the base parts 22 is preferably the samematerial as that of the aforementioned sheet 11, and particularlypreferred are elastomers. The sheet 11 and the base parts 22 includingthe same elastomer can be easily integrally molded together, so thatproductivity can be significantly increased. In other words, in one ofparticularly preferable embodiments, the sheet 11 and the resonantportions 21 (the base parts 22) are an integrally molded article inwhich the sheet 11 and the resonant portions 21 (the base parts 22) bothtogether include at least one selected from the group consisting ofthermosetting or photocurable elastomers and thermoplastic elastomers.Specific examples of the elastomers include rubbers, includingvulcanized rubbers such as chemically cross-linked natural rubber orsynthetic rubber, isoprene rubber, butadiene rubber, styrene-butadienerubber, chloroprene rubber, nitrile rubber, polyisobutylene rubber,ethylene propylene rubber, chlorosulfonated polyethylene rubber, acrylicrubber, fluorine rubber, epichlorohydrin rubber, polyester rubber,urethane rubber, silicone rubber, and modified products thereof; andpolymers such as polyacrylonitrile, polyethylene terephthalate,polybutylene terephthalate, polyvinyl chloride,polychlorotrifluoroethylene, polyethylene, polypropylene,polynorbornene, polyether ether ketone, polyphenylene sulfide,polyarylate, polycarbonate, polystyrene, epoxy resin, and oxazine resin,although not particularly limited thereto. Among these, preferred arenatural rubber, isoprene rubber, butadiene rubber, styrene-butadienerubber, chloroprene rubber, nitrile rubber, polyisobutylene rubber,ethylene propylene rubber, chlorosulfonated polyethylene rubber, acrylicrubber, fluorine rubber, epichlorohydrin rubber, polyester rubber,urethane rubber, silicone rubber, and modified products thereof, andmore preferred are silicone rubber, acrylic rubber, and modifiedproducts thereof from the viewpoints of excellent heat resistance,excellent cold resistance, and the like.

It is to be noted that the base parts 22 can be composed of a two-colormolded body or a multi-color molded body made of two or more polymermaterials. In this case, forming the base parts 22 on a side in contactwith the sheet 11 by using the same elastomer as that of the sheet 11 asdescribed above facilitates integral molding of the sheet 11 and thebase parts 22.

Note that, when providing the resonant portions 21 (the base parts 22)having a circular cross-sectional shape as in the present embodiment,among circles included in a cross section (a circular cross section)parallel to the sheet surface 11 a of the sheet 11 at the heightposition of the resonant portions 21 (the base parts 22) where the totalsum of cross-sectional areas of the plurality of resonant portions 21(the base parts 22) is at a maximum, the diameter of a circle having amaximum diameter is preferably 100 mm or less, more preferably 50 mm orless, and still more preferably 20 mm or less. Additionally, thediameter of a circle having a minimum diameter thereamong is preferably50 μm or more, more preferably 100 μm or more, and still more preferably1 mm or more. By setting the diameters within the above preferablenumerical ranges, a predetermined number or more of resonant portions 21(base parts 22) can be arranged on the sheet surface 11 a of the sheet11, whereby higher sound-insulating performance can be obtained, andmolding easiness and productivity also tend to be further improved.

[Weight Part]

The weight parts 23 are not particularly limited as long as they have alarger mass than the above-described base parts 22. In the presentembodiment, the weight parts 23 are formed into a substantiallycylindrical shape whose maximum diameter is smaller than the base parts22, and are embedded in the base parts 22 on leading end sides of theresonant portions 21. Thus, employing the structure in which the weightparts 23 working as the weights of the resonators are supported by thebase parts 22 determining the spring constant can facilitate, forexample, adjustment of the spring constant by changing the shape ormaterial (Young's modulus and mass) of the base parts 22 and control ofthe resonance frequency of the resonant portions 21 by changing the massof the weight parts 23. In general, when the Young's modulus of the baseparts 22 becomes small, the acoustic band gap tends to shift to a lowfrequency side. Additionally, when the mass of the weight parts 23becomes large, the acoustic band gap tends to shift to a low frequencyside.

The material forming the weight parts 23 can be selected as appropriatein consideration of mass, cost, and the like, and the kind of thematerial is not particularly limited. From the viewpoints of downsizing,improvement of sound-insulating performance, and the like of the soundinsulating sheet member 100 and the sound insulating structural body200, the material forming the weight parts 23 is preferably a materialhaving high specific gravity. Specific examples of the material includemetals such as aluminum, stainless steel, iron, tungsten, gold, silver,copper, lead, zinc, and brass or alloys thereof; inorganic glasses suchas soda glass, quartz glass, and lead glass; and composites includingpowders of these metals or alloys thereof, these inorganic glasses, orthe like in the polymer materials of the base parts 22 described above,although not particularly limited thereto. It is sufficient that thematerial, mass, and specific gravity of the weight parts 23 isdetermined such that the acoustic band gap between the sound insulatingsheet member 100 and the sound insulating structural body 200 iscoincident with a desired sound insulation frequency range. Among them,preferred is at least one selected from a group consisting of metals,alloys, and inorganic glasses from the viewpoints of low cost, highspecific gravity, and the like. Note that the specific gravity means theratio of the mass of the material to the mass of pure water at 4° C.under a pressure of 1013.25 hPa in a volume equal to the mass of thematerial, and the present specification uses values measured by JIS K0061 “Test methods for density and relative density of chemicalproducts”.

In the present embodiment, the weight parts 23 are embedded in the baseparts 22 on the leading end sides of the resonant portions 21, but thearrangement positions thereof are not particularly limited thereto.Although the arrangement positions vary depending on the shape, mass,Young's modulus, and the like of the base parts 22 and the weight parts23, the base parts 22 and the weight parts 23 are preferably arrangedsuch that the center of gravity (the center of mass) of the resonantportions 21 is located on the leading end sides thereof rather than atleast the center in the height direction of the resonant portions 21,from the viewpoints of thickness reduction, weight reduction, orimprovement of sound-insulating performance of the sound insulatingsheet member. Typically, the weight parts 23 may be offset on theleading end sides rather than the center in the height direction of theresonant portions 21. Note that each weight part 23 may be completelyembedded in the base part 22, only a part of the weight part 23 may beembedded therein, or may be provided on the base part 22 without beingembedded therein. Additionally, in the case of the base part 22 having abranched structure, when providing the weight part at a branch partformed from a branched point, the weight part 23 is preferably arrangedso as to be located on a leading end side of the branch part rather thanthe center thereof, from the viewpoint of weight reduction orimprovement of sound-insulating performance of the sound insulatingsheet member.

Note that although the plurality of resonant portions 21 are provided onthe sheet surface 11 a of the sheet 11, the material forming theresonant portions 21, the array, shape, size, arrangement direction, andthe like of the resonant portions 21 do not necessarily have to be thesame in all of the plurality of resonant portions 21. By making at leastone of the resonant portions 21 different in kind so that a plurality ofkinds of the resonant portions 21 are arranged, it is possible toenlarge a frequency region in which high sound-insulating performanceappears.

[Rib-Like Projecting Portions]

The sound insulating sheet member of the present invention may includerib-like projecting portions 31. In the present embodiment, the rib-likeprojecting portions 31 are each molded into a substantially plate-likeouter shape in such a manner as to extend in the length direction (asheet flow direction: MD direction) of the sheet 11. The rib-likeprojecting portions 31 are each provided on the sheet surface 11 a ofthe sheet 11, more specifically, at two edge portions in the widthdirection (a direction perpendicular to the sheet flow direction, thatis, TD direction) of the sheet 11.

The rib-like projecting portions 31 have a maximum height H2, which ishigher than the maximum height H1 of the resonant portions 21 describedabove, with respect to the normal direction of the sheet 11. Thus, evenwhen the sound insulating sheet member 100 is wound into the form of asheet or a plurality of the sound insulating sheet members 100 arestacked on each other, the resonant portions 21 are prevented fromcontacting with the back surface of the sheet 11 since the rib-likeprojecting portions 31 serve as spacers. Accordingly, providing therib-like projecting portions 31 facilitates manufacturing and storage ofthe sound insulating sheet member 100 in the so-called roll-to-rollmanner without causing manufacturing problems, such as deformation,variation, cracking, detachment, and breakage of the resonant portions21. Note that, it is sufficient that the maximum height H2 of therib-like projecting portions 31 is higher than the maximum height H1 ofthe resonant portions 21, and it is not particularly limited. From theviewpoints of molding easiness, productivity improvement, and the like,the maximum height H2 is preferably from 50 μm to 100 mm, morepreferably from 100 μm to 50 mm, and still more preferably from 1 mm to20 mm.

The shape and arrangement position of the rib-like projecting portions31 are not particularly limited as long as they are arranged so as notto interfere with the resonant portions 21 working as the resonators.For example, the outer shape of the rib-like projecting portions 31 isnot particularly limited, and any shape can be employed, such as any ofpolygonal prism-like shapes, such as a triangular prism-like shape, arectangular prism-like shape, a trapezoidal prism-like shape, apentagonal prism-like shape, and a hexagonal prism-like shape,cylindrical shapes, elliptic cylindrical shapes, truncated pyramidshapes, truncated cone shapes, pyramid shapes, cone shapes, hollowtubular shapes, and irregular shapes that are not classified into theseshapes. The rib-like projecting portions 31 can also be formed into acolumnar shape having a cross-sectional area and/or a cross-sectionalshape varying depending on the height position of the rib-likeprojecting portions 31. In addition, it is sufficient that the maximumlength of the rib-like projecting portions 31 in the length direction ofthe sheet 11 is not particularly limited as long as it is equal to orless than the maximum length in the MD direction of the sheet.

Note that although the present embodiment uses the pair of rib-likeprojecting portions 31 extending in the length direction of the sheet11, a plurality of rib-like projecting portions 31 having a maximumlength shorter than the pair thereof may be arranged apart along thelength direction of the sheet 11. In this case, the arrangement intervalbetween the respective rib-like projecting portions 31 may be periodicor at random. When arranging the plurality of rib-like projectingportions 31 apart from each other in this way, the distance between therespective rib-like projecting portions 31 is preferably 100 cm or less,more preferably 50 cm or less, and still more preferably 10 cm or less,although not particularly limited.

The material forming the rib-like projecting portions 31 is preferablythe same polymer material as that of the sheet 11 and/or the base parts22, and more preferably the same elastomer as that of the sheet 11and/or the base parts 22, although not particularly limited. Employingthe same polymer material as that of the sheet 11 and/or the base parts22 facilitates integral molding thereof with the sheet 11 and/or thebase parts 22, thereby significantly increasing productivity.

[Support Body]

The sound insulating sheet member of the present invention can beinstalled as appropriate according to an environment wheresound-insulating performance is exhibited. For example, the soundinsulating sheet member may be directly installed on a device, astructural body, or the like. An adhesion layer or the like may beprovided between the sound insulating sheet member and the device, thestructural body, or the like. Additionally, the sound insulating sheetmember may be used in such a manner that the sound insulating sheetmember is supported by a support body. When insulating sound by usingthe sound insulating sheet member of the present invention, it issufficient that the support body supports the sound insulating sheetmember, and the sound insulating sheet member does not have to besupported by the support body in situations such as being manufacturedand stored.

It is sufficient that the support body is provided in contact with atleast one surface of the sheet of the sound insulating sheet member. Thesupport body may be provided on the sheet surface with which theresonant portions are provided in contact and/or a surface opposite tothe sheet surface with which the resonant portions are provided incontact.

In the present embodiment, the support body 51 is provided on the backsurface 11 b side of the above sheet 11. The material forming thesupport body 51 is not particularly limited as long as it can supportthe sheet 11, but preferably one having a higher rigidity than the sheet11 from the viewpoint of enhancement of sound-insulating performance.Specifically, the support body 51 preferably has a Young's modulus of 1GPa or more, and more preferably 1.5 GPa or more. Although there is noparticular upper limit, for example, the Young's modulus of the supportbody 51 may be 1000 GPa or less.

In addition, when directly installing the sound insulating sheet memberon a device, a structural body, or the like, the surface where the soundinsulating sheet member is to be installed preferably has the samerigidity as that of the above support body from the viewpoints ofsupport of the sheet, enhancement of the sound-insulating performance,and the like.

Specific examples of the material forming the support body 51 includeorganic materials such as polyacrylonitrile, polyethylene naphthalate,polyvinyl chloride, polyvinylidene chloride,polychlorotrifluoroethylene, polyethylene, polypropylene, polystyrene,cyclicpolyolefin, polynorbornene, polyether sulfone, polyether etherketone, polyphenylene sulfide, polyarylate, polycarbonate, polyamide,polyimide, triacetyl cellulose, polystyrene, epoxy resins, acrylicresins, and oxazine resins, and composite materials including a metalsuch as aluminum, stainless steel, iron, copper, zinc, or brass, aninorganic glass, inorganic particles, or fiber in these organicmaterials, although not particularly limited thereto. Among them, fromthe viewpoints of sound-insulating properties, rigidity, moldability,cost, and the like, the support body is preferably at least one selectedfrom a group consisting of photocurable resin sheets, thermosettingresin sheets, thermoplastic resin sheets, metal plates, and alloyplates. Herein, the thickness of the support body 51 is generallypreferably from 0.1 mm to 50 mm from the viewpoints of sound insulatingproperties, rigidity, moldability, weight reduction, cost, and the like,although not particularly limited.

Note that the shape of the support body 51 can be set as appropriateaccording to the surface for installing the sound insulating structuralbody 200, and is not particularly limited. For example, the shape of thesupport body 51 may be a flat sheet shape, a curved sheet shape, or aspecial shape processed so as to have a curved surface part, a foldedpart, or the like. Furthermore, from the viewpoints of weight reductionand the like, a cutout portion, a punched-out portion, or the like maybe provided at anyplace of the support body 51.

Second Embodiment

FIG. 7 and FIG. 8 are a schematic perspective view illustrating a soundinsulating sheet member 101 and a sound insulating structural body 201of the present embodiment and a cross-sectional view taken along arrowsthereof. The present embodiment has the same structure as the soundinsulating sheet member 100 and the sound insulating structural body 200of the above-described first embodiment, except that the number ofresonant portions arranged, the shapes of base parts and weight parts,and the shape and number of rib-like projecting portions arranged aredifferent. Thus, redundant description thereof will be omitted here.

Each of the resonant portions 21 of the present embodiment is formed bya composite structure including abase part 24 and a weight part 25supported by the base part 24 and having a larger mass than the basepart 24. Even in the present embodiment, a plurality of the base parts24 having a substantially cylindrical outer shape are provided incontact with the sheet surface 11 a of the sheet 11.

As illustrated in FIG. 9 , each weight part 25 includes a protrudingpart 25 a having a substantially conical shape provided toward the basepart 24. The weight part 25 is supported on an upper surface side of thebase part 24 in a state where the protruding part 25 a is embedded inthe base part 24. Even in this structure, detachment of the weight part25 is prevented. Note that the shape of the protruding part 25 a is notparticularly limited as long as it is provided toward the base part 24.For example, as illustrated in FIG. and FIG. 11 , a protruding part 25 bhaving a cylindrical shape or a protruding part 25 c having a hollowtubular shape may be provided. Other than these, for example, any shapecan be employed such as any of spherical shapes, semi-spherical shapes,elliptic spherical shapes, polygonal prism-like shapes such as atriangular prism-like shape, a rectangular prism-like shape, atrapezoidal prism-like shape, a pentagonal prism-like shape, and ahexagonal prism-like shape, elliptic cylindrical shapes, truncatedpyramid shapes, truncated conical shapes, pyramid shapes, and irregularshapes that are not classified into these shapes.

On the other hand, rib-like projecting portions 32 of the presentembodiment are formed by being molded into a substantially cylindricalouter shape, and arranged apart so as to each form a line along thelength direction (the sheet flow direction: MD direction) of the sheet11 at edge portions in the width direction (the direction perpendicularto the sheet flow direction, that is, TD direction) of the sheet 11.

Even in the present embodiment, the same functions and effects as thoseof the above-described first embodiment are achieved. In addition tothem, followability (flexibility) of the sound insulating sheet member101 is further increased since the plurality of rib-like projectingportions 32 are arranged apart so as to form the line in the presentembodiment. Thus, even if an attachment surface has a more intricateshape, the flexible sheet 11, which is stretchable, can follow thesurface shape, as a result of which the sheet 11 can be stably attachedonto the support body 51.

Third Embodiment

FIG. 19 is a schematic perspective view illustrating a sound insulatingsheet member 102 of the present embodiment, and FIG. 20 is across-sectional view taken along arrows XX-XX thereof. The soundinsulating sheet member 102 includes the sheet 11 having rubberelasticity and the plurality of resonant portions 21 provided on thesheet surface Ila of the sheet 11. The present embodiment has the samestructures as the sound insulating sheet member 100 or 101 and the soundinsulating structural body 200 or 201 of the first and secondembodiments described above, except for the number of the resonantportions arranged, the shapes of the base parts and the weight parts,and the absence of rib-like projecting portions and a support body.Thus, redundant description thereof will be omitted here.

In the present embodiment, each base part 22 is substantiallycylindrical, and a part of the base part 22 on a side opposite to abottom surface in contact with the sheet surface 11 a has asemi-spherical outer shape. The outer shape of the base part is notparticularly limited, and the shape of the part thereof on the sideopposite to the bottom surface in contact with the sheet surface 11 a isalso not particularly limited. The outer shape of the base part can beadjusted, as appropriate, into a shape, for example, such as asemi-spherical shape, a flat surface shape, a protruding shape, or arecessed shape.

The outer shape of the weight part is also not particularly limited, andcan be adjusted, as appropriate, into a shape such as a spherical shape,a semi-spherical shape, a polyhedron such as a cube or a rectangularparallelepiped, or a plate-like shape.

[Manufacturing Method]

The method for manufacturing the sound insulating sheet member and thesound insulating structural body of the present invention are notparticularly limited, and for example, may include the following steps(1) to (4):

-   -   (1) a step of preparing a mold provided with a plurality of        cavities and arranging a weight in each of the plurality of        cavities provided in the mold;    -   (2) a step of pouring a resin material and/or polymer material        in the cavities;    -   (3) a step of curing the poured resin material and/or polymer        material: and    -   (4) a step of releasing the resulting cured article from the        mold.

The above steps (1) to (4) can be performed in accordance withdescription of the manufacturing methods given in embodiments that willbe described later.

In the step (2), the shape of the cavities is not particularly limited,but for example, the shape of the bottoms can be selected asappropriate, such as a semi-spherical shape, a flat surface shape, aprotruding shape, or a recessed shape. For example, when the shape ofthe cavities is semi-spherical, the position of the weight arranged inthe cavities is easily set at a top point of the semi-spherical shape,so that the position of the weight part in each of the plurality ofresonant portions provided on the sound insulating sheet member tends tobe easily constant.

Using the above-described first embodiment, one embodiment of the methodfor manufacturing the sound insulating sheet member will be given. Themethod for manufacturing the sound insulating sheet member and the soundinsulating structural body of the present invention are not limitedthereto. Additionally, the embodiment can also be appliedcorrespondingly to other embodiments, as appropriate.

The sound insulating sheet member 100 can be obtained by providing theabove-described resonant portions 21 and rib-like projecting portions 31on the sheet surface 11 a of the sheet 11. The method for arranging theresonant portions 21 and the rib-like projecting portions 31 is notparticularly limited. Examples of the method include a method ofthermally pressurizing or pressurizing separately molded respectiveparts to pressure-bond, a method of adhering by using any of variouswell-known adhesives, and methods of bonding by heat welding, ultrasonicwelding, laser welding, or the like. Examples of the adhesives includeepoxy resin-based adhesives, acrylic resin-based adhesives, polyurethaneresin-based adhesives, silicone resin-based adhesives, polyolefinresin-based adhesives, polyvinyl butyral resin-based adhesives, andmixtures thereof, although not particularly limited thereto. Note that apart or the entire part of each resonant portion 21, and the rib-likeprojecting portions 31 can also be formed by punching out a rubber plateobtained by the above-described molding method. Additionally, when apart of each resonant portion 21 is composed of a metal or alloy, thepart thereof can be formed by cutting out or the like of the metal oralloy.

From the viewpoints of improvements in productivity and economicefficiency and the like, preferred is a method of integrally molding thesound insulating sheet member 100 by die molding, cast molding, or thelike. One example thereof is a method of molding an integrally moldedarticle of the sheet 11, the resonant portions 21, and the rib-likeprojecting portions 31 by using a mold or a cast provided with cavitieshaving a shape corresponding to the integrally molded article of thesheet 11, the resonant portions 21, and the rib-like projecting portions31. As such an integrally molding method, various kinds of methods areknown, such as press molding, compression molding, cast molding,extrusion molding, and injection molding, and the kind of the integrallymolding method is not particularly limited. Note that when the rawmaterial of each component is, for example, a resin material or apolymer material having rubber elasticity, it can be poured in the formof a liquid precursor or thermally molten material into the cavities.Alternatively, when the raw material is a metal, an alloy, or aninorganic glass, it can be previously arranged (inserted) in apredetermined position in the cavities.

The resin material and the polymer material are not particularlylimited. Examples thereof include materials exemplified for the sheet,which uses the sound insulating sheet member of the present invention,the base parts, and the like, and raw materials, intermediate products,and the like thereof.

FIG. 3 to FIG. 6 are diagrams illustrating one example of the steps ofmanufacturing the sound insulating sheet member 100. Herein, using amold 61 with cavities 61 a having a shape corresponding to the resonantportions 21 and cavities 61 b having a shape corresponding to therib-like projecting portions 31 described above (see FIG. 3 ), theweight part 23 is arranged in each cavity 61 a of the mold 61 (see FIG.4 ). After that, a resin material having rubber elasticity is pouredinto the cavities 61 a and 61 b, and heating or pressurization isperformed as needed (see FIG. 5 ). Then, the integrally molded articleof the sheet 11, the resonant portions 21, and the rib-like projectingportions 31 is released from the mold to obtain the sound insulatingsheet member 100. Such an integrally molding method can improveproductivity and economic efficiency, as well as can facilitate moldingfor even an intricate shape, and the obtained sound insulating sheetmember 100 tends to be excellent in mechanical strength due to enhancedadhesion strength between the respective components. From theseviewpoints also, the sheet 11, the resonant portions 21, and therib-like projecting portions 31 are preferably an integrally moldedarticle including a thermosetting elastomer and/or thermoplasticelastomer.

[Functions and Effects]

The sound insulating sheet members 100 to 103 and the sound insulatingstructural bodies 200 to 201 of the present embodiment are configuredsuch that the plurality of resonant portions 21 are provided in contactwith the sheet surface 11 a of the sheet 11 having rubber elasticity.Thus, when a sound wave is input from a noise source, highsound-insulating performance exceeding the mass law can be obtained.Herein, in the sound insulating sheet members 100 to 103 and the soundinsulating structural bodies 200 to 201 of the present embodiment,adjustment of the spring constant by changing of the shape or material(Young's modulus or mass) of the base parts 22 and control of theresonance frequency of the resonant portions 21 by changing of the massof the weight parts 23 or the like can be easily performed. Moreover,the frequency band (the acoustic band gap width and the frequencyposition) can be controlled even by the material, thickness, and thelike of the sheet 11. Accordingly, the sound insulating sheet members100 to 103 and the sound insulating structural bodies 200 to 201 of thepresent embodiment are excellent in flexibility of sound insulationfrequency selection and design flexibility as compared to theconventional ones.

Additionally, in the sound insulating sheet members 100 to 103 and thesound insulating structural bodies 200 to 201 of the present embodiment,the resonant portions 21 and the rib-like projecting portions 31 areprovided in contact with the sheet surface 11 a on one side of the sheet11 having rubber elasticity, and not provided on the sheet surface 11 bon the other side thereof. Thus, even when the support body 51 is anon-flat surface having, for example, a curved surface or the like, theflexible sheet 11, which is stretchable, can follow the surface shapethereof, as a result of which the sheet 11 can be stably attached ontothe support body 51. Accordingly, the sound insulating sheet members 100to 103 and the sound insulating structural bodies 200 to 201 of thepresent embodiment are excellent in handleability and versatility ascompared to the conventional ones.

Additionally, when the sheet 11 and the resonant portions 21 areintegrally molded, the plurality of resonant portions 21 (resonators)can be arranged at once, so that productivity and handleability can besignificantly improved.

There are arranged the rib-like projecting portions 31 having themaximum height H2 higher than the maximum height H1 of the resonantportions 21. Thus, even when each of the sound insulating sheet members100 to 103 is wound into the form of a sheet or a plurality of therespective sheet members are stacked on each other, the rib-likeprojecting portions 31 serve as spacers to prevent the resonant portions21 from contacting with the back surface of the sheet 11. Accordingly,without causing manufacturing problems such as deformation,modification, cracking, detachment, and breakage of the resonantportions 21, the sound insulating sheet members 100 to 103 can be easilycontinuously produced and stored in the so-called roll-to-roll manner,whereby productivity speed is improved as compared to sheet-by-sheetbatch production, so that productivity and economic efficiency can beimproved.

[Sound Insulating Structural Body]

The sound insulating sheet member of the present invention can be usedas a sound insulating structural body. As described in the aboveembodiments, the sound insulating structural body may include a supportbody, rib-like projecting portions, and the like.

Additionally, as one example of a method for using the sound insulatingsheet member of the present invention, it can be considered that thesheet member is used to reduce or eliminate sounds generated frommachinery or equipment, such as a motor and a pump, and sounds generatedfrom metal pipes or resin pipes by attaching to the main body or thecover of the machinery or equipment or winding around the metal pipes,the resin pipes, or the like.

As the sound insulating structural body, the sound insulating sheetmember of the present invention may be a sound insulating structuralbody including the sound insulating sheet member and a flame retardantand/or nonflammable member. Using the sheet member in combination with aflame retardant and/or nonflammable member enables the sheet member tobe used as a structural body for architecture or the like having a soundinsulating function and a fire protecting function. The configurations,positions, and the like of the sound insulating sheet member and theflame retardant and/or nonflammable member forming the sound insulatingstructural body are not particularly limited. For example, the flameretardant and/or nonflammable member may be used as a support body toprovide the sound insulating sheet member on the support body, or thesound insulating sheet member may be provided in a case composed of theflame retardant and/or nonflammable member.

The flame retardant and/or nonflammable case is a member that is curedby heating and not melted even by high temperature heat in case of fireor a member that keeps a certain shape without being flammable for acertain length of time even when fire heat is applied, and that isformed by a thermosetting resin composition or a flame retardantmaterial (including quasi-nonflammable materials and nonflammablematerials).

The thermosetting resin composition is not particularly limited, andexamples thereof include thermosetting acrylic resin compositions andthermosetting epoxy resin compositions, and polyimide-based resins,which have high heat resistance.

Examples of the flame retardant materials include inorganic fibers suchas glass wool, rock wool, ceramic wool, siliceous fiber, carbon fiber,silica alumina fiber, alumina fiber, and silica fiber, products obtainedby processing gypsum, concrete, or the like into planar shapes orproducts obtained by adding the above-mentioned inorganic fibers togypsum, concrete, or the like and processing the mixtures into planarshapes, and flame retardant resin compositions obtained by adding aflame retardant such as red phosphorus to metals such as steel, iron,copper, and aluminum, an aluminum glass cloth, and a resin componentsuch as urethane resin.

The sound insulating structural body may be a layered body including thesound insulating sheet member of the present invention. For example, asin the cross-sectional view of a sound insulating structural bodyillustrated in FIG. 21 , the sound insulating structural body may be oneformed by providing the sound insulating sheet member 102 on bothsurfaces of the support body 51, i.e., a sound insulating structuralbody formed by allowing the two sheet surfaces 11 b of the soundinsulating sheet member 102 to face each other to have the support body51 therebetween. Alternatively, a plurality of sound insulatingstructural bodies each including the sound insulating sheet memberprovided on a support body may be stacked on each other for use.Combining the plurality of sound insulating sheet members enablescontrol of the acoustic band gap width, the frequency position, and thelike.

EXAMPLES

Hereinafter, the present invention will be described more specificallyby way of Examples. However, the present invention is not limitedthereby at all. The present invention can employ various conditions aslong as the object of the invention is achieved without departing thescope of the invention.

Example 1

Sylgard 184 (Dow Corning Toray Co., Ltd.) was poured into astainless-steel vessel and heated at 150° C. for 15 minutes to produce asilicone rubber sheet having a thickness of 3 mm. The Young's modulus ofthe produced silicone rubber was measured by a dynamic viscoelasticityanalyzer DVA-200s (manufactured by IT Keisoku Seigyo Co., Ltd.) andfound to be 10 MPa at 25° C. and 10 Hz. Additionally, the densitythereof was 1.04 g/cm³. After that, the silicone rubber sheet waspunched out into a cylindrical shape having a diameter of 6 mm and aheight of 3 mm to produce base parts of resonant protruding portions.The mass per base part of the resonant protruding portions was 0.09 g.In addition, tungsten having a density of 19.3 g/cm³ was cut into acylindrical shape having a diameter of 6 mm and a height of 3 mm toproduce weight parts of the resonant protruding portions. The mass perweight part of the resonant protruding portions was 1.6 g.

The obtained cylindrical base parts were pressure-bonded onto a siliconerubber sheet (manufactured by Mitsubishi Plastics, Inc) having athickness of 0.2 mm and a Young's modulus of 3.4 MPa (25° C. and 10 Hz).Next, the cylindrical weight parts were pressure-bonded onto an uppersurface of the cylindrical base parts to produce a sound insulatingsheet member of Example 1. Then, the obtained sound insulating sheetmember was pressure-bonded and attached to an aluminum plate having athickness of 0.5 mm to produce a sound insulating structural body ofExample 1.

Comparative Examples 1 to 3

All of the resonant portions were removed from the sound insulatingstructural body of Example 1 to produce a sound insulating structuralbody of Comparative Example 1. Additionally, without using a siliconerubber sheet having a thickness of 0.2 mm, the base parts were directlypressure-bonded onto an aluminum plate having a thickness of 0.5 mm, andthe cylindrical weight parts were adhered to the upper surfaces of thebase parts to produce a sound insulating structural body of ComparativeExample 2. Furthermore, the weight parts were adhered onto an aluminumplate having a thickness of 0.5 mm by ARON ALPHA 201 (manufactured byToagosei Co., Ltd) to produce a sound insulating structural body ofComparative Example 3.

Comparative Examples 4 to 5

The cylindrical weight parts made of tungsten in Example 1 werepressure-bonded onto a silicone rubber sheet (manufactured by MitsubishiPlastics, Inc.) having a thickness of 0.2 mm and a Young's modulus of3.4 MPa (25□DC and 10 Hz) to produce a sound insulating sheet member.Then, the obtained sound insulating sheet member was pressure-bonded andattached to an aluminum plate having a thickness of 0.5 mm to produce asound insulating structural body of Comparative Example 4.

Additionally, the cylindrical base parts made of the silicone rubber inExample 1 were pressure-bonded onto a silicone rubber sheet(manufactured by Mitsubishi Plastics, Inc.) having a thickness of 0.2 mmand a Young's modulus of 3.4 MPa (25□C and 10 Hz) to produce a soundinsulating sheet member. Then, the obtained sound insulating sheetmember was pressure-bonded and attached to an aluminum plate having athickness of 0.5 mm to produce a sound insulating structural body ofComparative Example 5.

Note that the sound insulating structural bodies of Example 1 andComparative Examples 1 to 5 had a plate shape having a size of 300mm×200 mm in plan view. In addition, in each of the sound insulatingstructural bodies of Example 1 and Comparative Examples 2 to 5, 100resonant protruding portions (a lattice-like array composed of 10 piecesin the sheet length direction×10 pieces in the sheet width direction)were provided in a 100×100 mm region of a sheet center portion.

[Sound-Insulating Performance]

The produced sound insulating structural bodies each were mounted to anopening portion (210 mm×300 mm) of an upper part of a sound sourcechamber having an internal size of 700 mm×600 mm×500 mm (volume: 0.21m³), and vibration amplitude in the out-of-plane direction of the sheetsurface where the resonant portions were not overlapping at a centerportion of the sound insulating structural body was measured using alaser Doppler vibrometer (OFV2500, CLV700 (Polytec Co., Ltd.)). Whitenoise was radiated from a speaker (101 MM (Bose Co., Ltd.) installed inthe sound source chamber so that a sound wave was input to a test bodyfrom random directions. FIGS. 12 to 17 depict results of themeasurement.

When compared between Example 1 and Comparative Example 1, it wasconfirmed that due to the presence of the resonant portions, a vibrationsuppressing region appeared near 1 to 2 kHz. Additionally, when comparedbetween Example 1 and Comparative Example 2, it was confirmed that, inboth of the structure of the conventional technique including theplurality of resonators directly adhered onto the aluminum plate and thestructure of the present invention including the plurality of resonantportions provided on the sheet having rubber elasticity, a vibrationreducing region similarly appeared near 1 to 2 kHz. This has proved thatthe present invention has a sound insulating performance equivalent tothat of the conventional technique.

In addition, when compared between Example 1 and Comparative Example 3,it was confirmed that even though both structures were substantiallyequal in area density, the structure including the plurality ofcylindrical weight parts directly adhered onto the aluminum plate had noappearance of vibration reduction near 1 to 2 kHz. This has proved thatthe sound insulating sheet member and the sound insulating structuralbody of the present invention exhibit behaviors that exceed mass law.

Furthermore, when compared between Example 1 and Comparative Example 4,it was confirmed that the structure without any cylindrical base partsdid not have conspicuous vibration reduction near 1 to 2 kHz. This hasproved that the resonant portions need to be provided with base parts.

In addition, when compared between Example 1 and Comparative Example 5,it was confirmed that the structure without any cylindrical weight partshad no appearance of vibration reduction near 1 to 2 kHz. This hasproved that the resonant portions need to be provided with weight parts.

[Acoustic Band Gap]

Next, acoustic band gap estimation was estimated by a finite elementmethod by the method described in Non-Patent Literature 3. FIG. 18illustrates schematic view of unit cells of each structure, and Table 1depicts results of the acoustic band gap estimation, together withsizes, materials, and physical properties of constituent members.

TABLE 1 Specific Young's gravity modulus Poisson Acoustic Part r/mm h/mma/mm Material g/cm3 Mpa coefficient band gap Estimated i 3 3 — Iron 7.85211000 0.29 780-960 Hz Structure 1 ii 3 3 — Rubber 1.05 1 0.49 iii — 0.210 Rubber 1.05 1 0.49 iv — 0.5 10 Aluminum 2.7 63300 0.36 Estimated i 33 — Iron 7.85 211000 0.29 755-910 Hz Structure 2 ii 3 3 — Rubber 1.05 10.49 iii — 0.5 10 Rubber 1.05 1 0.49 iv — 0.5 10 Aluminum 2.7 63300 0.36Estimated i 3 3 — Iron 7.85 211000 0.29  755-1000 Hz Structure 3 ii 3 3— Rubber 1.05 1 0.49 iii — 0.5 10 Rubber 1.05 1 0.49 iv — 0.5 10Polycarbonate 1.2 2300 0.39 Estimated i 3 3 — Iron 7.85 211000 0.292390-2880 Hz Structure 4 ii 3 3 — Rubber 1.05 10 0.49 iii — 0.5 10Rubber 1.05 10 0.49 iv — 0.5 10 Aluminum 2.7 63300 0.36 Estimated i 3 3— Iron 7.85 211000 0.29 1890-2190 Hz Structure 5 ii 3 3 — Rubber 1.05 100.49 iii — 0.5 10 Rubber 1.05 1 0.49 iv — 0.5 10 Aluminum 2.7 63300 0.36Comparative i 3 3 — Iron 7.85 211000 0.29  800-1000 Hz Structure 1 ii 33 — Rubber 1.05 1 0.49 iii — 0.5 10 Aluminum 2.7 63300 0.36

When compared between Estimated Structures 1 and 2 and ComparativeStructure 1, the acoustic band gap of the sound insulating sheet memberincluding the plurality of resonant portions provided on the sheethaving rubber elasticity has shifted to a low frequency side as thethickness of the sheet has increased from 0.2 mmt to 0.5 mmt. The aboveresult confirmed that the acoustic band gap can be controlled by thethickness of the sheet, and thus design flexibility of the soundinsulating sheet member is increased.

Furthermore, Estimated Structures 4 and 5 indicate that reducing theYoung's modulus of the sheet from 10 MPa to 1 MPa has caused theacoustic band gap to shift to a low frequency side. The above resultconfirmed that the acoustic band gap can be controlled by the Young'smodulus of the sheet, and thus design flexibility of the soundinsulating sheet member is increased.

REFERENCE SIGNS LIST

-   -   11: Sheet    -   11 a: Sheet surface    -   11 b: Sheet surface    -   21: Resonant portion    -   22: Base part    -   23: Weight part    -   24: Base part    -   25: Weight part    -   25 a: Protruding part    -   25 b: Protruding part    -   25 c: Protruding part    -   31: Rib-like projecting portion    -   32: Rib-like projecting portion    -   51: Support body    -   61: Mold    -   61 a: Cavity    -   61 b: Cavity    -   100: Sound insulating sheet member    -   101: Sound insulating sheet member    -   102: Sound insulating sheet member    -   200: Sound insulating structural body    -   201: Sound insulating structural body    -   202: Sound insulating structural body    -   H1: Maximum height    -   H2: Maximum height    -   r: Radius    -   h: Height    -   a: Sheet length    -   i: Weight part    -   ii: Base part    -   iii: Sheet    -   iv: Support body

1. A structural body, comprising: a sheet member comprising a sheet having rubber elasticity and a resonant portion in contact with a surface of the sheet; and a support body in contact with a surface of the sheet opposite to the surface contacting the resonant portion; wherein the resonant portion includes a base part and a weight part supported by the base part, a mass of the weight part is larger than a mass of the base part, and a thickness of the sheet is 1 mm or less.
 2. The structural body according to claim 1, wherein the weight part is arranged such that a center of gravity of the resonant portion is located on a leading end side of the resonant portion.
 3. The structural body according to claim 1, wherein the sheet comprises at least one elastomer selected from the group consisting of a thermosetting elastomer, a photocurable elastomer and a thermoplastic elastomer.
 4. The structural body according to claim 1, wherein the sheet has a Young's modulus of from 0.01 MPa to 100 MPa.
 5. The structural body according to claim 1, wherein the base part comprises at least one material selected from the group consisting of a thermosetting elastomer, a photocurable elastomer, a thermoplastic elastomer, a thermosetting resin, a photocurable resin, and a thermoplastic resin.
 6. The structural body according to claim 1, wherein the sheet and the resonant portion are an integrally molded article, and the sheet and the resonant portion both together comprise at least one elastomer selected from the group consisting of a thermosetting elastomer, a photocurable elastomer and a thermoplastic elastomer.
 7. The structural body according to claim 1, wherein the weight part comprises at least one selected from the group consisting of a metal, an alloy, and an inorganic glass.
 8. The structural body according to claim 1, wherein the weight part includes a protruding part provided toward the base part.
 9. The structural body according to claim 1, wherein at least a part of the weight part is embedded in the base part on a leading end side of the resonant portion.
 10. The structural body according to claim 1, further comprising at least one rib-like projecting portion, wherein the rib-like projecting portion is in contact with the sheet surface contacting the resonant portion, and a height of the at least one rib-like projecting portion is higher than the resonant portion in a sheet normal direction.
 11. The structural body according to claim 10, wherein the at least one rib-like projecting portion is provided so as to extend in a length direction of the sheet.
 12. The structural body according to claim 10, comprising a plurality of the rib-like projecting portions which are spaced apart along the length direction of the sheet.
 13. The structural body according to claim 10, wherein the sheet, the resonant portion, and the at least one rib-like projecting portion are an integrally molded article, and the sheet, the resonant portion, and the at least one rib-like projecting portion all together comprise at least one elastomer selected from the group consisting of a thermosetting elastomer, a photocurable elastomer and a thermoplastic elastomer.
 14. The structural body according to claim 1, further comprising a flame retardant and/or a nonflammable member.
 15. A sound insulating member comprising the structural body according to claim
 1. 16. A vibration damping member comprising the structural body according to claim
 1. 17. A vibration damping and sound insulating member comprising the structural body according to claim
 1. 